Itemscope validation

Greetings to the Validator.nu staff.
I just tried a validation via direct input on the "validator.w3.org/nu"
feature. My interest was to check the behavior of the service against the
"itemscope/itemprop/property" scheme. As of yet I don't know Schema.org
specification well enough but I have found an erratic behavior. It seems
that the validator considers correct the @itemprop and @property if they
are used in alternate elements. Below the full document i validated first:
---

<html itemscope itemtype="http://schema.org/WebPage" xmlns:fb="
https://www.facebook.com/2008/fbml">
  <head>
    <title>An Example Title</title>
    <meta content="An Example Title" itemprop="name" property="og:title" />
    <meta content="Lorem ipsum dolor sit amet" itemprop="description"
name="description" property="og:description" />
    <meta content="http://www.example.com/image.jpg" itemprop="image"
property="og:image" />
    <meta content="http://www.example.com/permalink" itemprop="url"
property="og:url" />
    <link rel="canonical" href="http://www.example.com/permalink" />
  </head>
  <body>
    ...content...
  </body>
</html>

---

Based on the errors presented by the validator I tried this version of the
same document:
---

<!DOCTYPE html>
<html itemscope itemtype="http://schema.org/WebPage" xmlns="
http://www.w3.org/1999/xhtml">
  <head>
    <title>An Example Title</title>
    <meta itemprop="name" content="An Example Title" />
    <meta name="description" property="og:description" content="Lorem ipsum
dolor sit amet" />
    <meta itemprop="image" content="http://www.example.com/image.jpg" />
    <link rel="canonical" property="og:url" href="
http://www.example.com/permalink" />
  </head>
  <body>
    ...content...
  </body>
</html>

---
The latter results correct. But, basing on the Schema.org semantic metadata
specification, each semantic element should possess the "itemprop/property"
attributes pair. Can you explain the error or fix the bug, if any?

Also, notice that in the first version of the document the attribute
xmlns:fb="https://www.facebook.com/2008/fbml" is present. The validation
result states that it is both not allowed and not serializable due to its
local name. Is this correct? Shouldn't HTML5 allow namespace-specific
attributes via prefix?
Thank you in advance.

*Andrea Rendine*

Received on Sunday, 18 August 2013 20:57:17 UTC